John Morrison

Himself - Presenter / Narrator

Peter Jay

Himself - DCI, Metropolitan Police, 1983

Iain MacDhùghaill

Himself - Criminal Defence Lawyer

Archie MacLullich

Himself - Consultant Psychologist

Pàdraig MacAmhlaigh

Himself - Journalist

Julian Booth

Himself - Forensic Psychologist

Brian Masters

Himself - Author, 'Killing for Company - The Case of Dennis Nilsen'

Elizabeth Scott

Herself - Nilsen's Mother

Neil McKinven

Dennis Nilsen

Ryan Fletcher

Victim Jamie

John Paul Hurley

DCS Chambers

Lewis Brown

Young Nilsen

Finlay McLean

Nilsen's Grandfather

Nicholas Underwood

DCI Peter Jay

Andy Marjoribanks

Solicitor